Here is the real quote from NFPA's website.
NFPA has no record of a fire killing more than two people in a completely
sprinklered public assembly, educational, institutional or residential
building where the system was working properly.
David Autry
Plans Examiner
Nebraska State Fire Marshal's Office
246 S. 14th Street
Lincoln, NE 68508
402-471-9659
402-471-3118 fax
www.sfm.ne.gov
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Paul Pinigis
Sent: Friday, March 16, 2007 11:02 AM
To: [email protected]
Subject: RE: Minimum Supply Pressure
Those statistics were given to me by Factory Mutual when I worked for
their Pittsburgh office. I have never heard the one about no
multi-death fires in sprinkered buildings, so I can't help you there.
Paul J. Pinigis, P.E.
Chief Life Safety Engineer
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Joe
Hankins
Sent: Friday, March 16, 2007 11:56 AM
To: [email protected]
Subject: Re: Minimum Supply Pressure
Paul,
Could you pleas provide the source of your statistics? I've heard them
quoted many, many times, but never found anyone who could point to the
actual data behind them. There is another one going around for years
that says there has never been a multiple-death fire in a sprinklered
building. That one is definitely not true.
Before we start talking about "overkill" in sprinkler designs we need to
recognize that some current standards have large safety factors, some
have none, and most have unknown safety factors.
The idea that there is a huge difference between a 5-sprinkler fire and
a 15- or 30-sprinkler fire seems logical on the surface, but if you know
how sprinklers operate, you know they operate in rings. The heat that
operates sprinklers spreads in a circle from the fire origin. For
symetrically-spaced sprinkler system where the fire starts centered
among 4 sprinklers, there are 4 sprinklers in the first ring around
ignition, so there is virtually no difference between a 1-sprinkler
fire and a 4-sprinkler fire. If those sprinklers don't control the fire,
then any (and all) of the 12 sprinklers in the next ring can operate,
meaning that there is very little difference betwen a 5-sprinkler fire
and a 16 sprinkler fire. If you get into the next ring, then the number
is 36 sprinklers. So, the 1-ring "safety factor" between 4 and 16
sprinklers is the same as the 1-ring safety factor between 16 and 36
sprinklers. A 1-ring "safety factor" is not overkill in my book!
Finally, the "cushion" sometimes applied to a water supply is not a
safety factor. In addition to accounting for seasonal, weekly, daily,
and hourly fluctuations, it is a recognition that water supplies
invariably deteriorate and an attempt to avoid the large cost of
upgrading the system or water supply when it does. I'll agree that
adding a cushion to a fire pump supply dedicated solely to a fire
protection system is not necessary, because the pump supply stays the
same unless there is a problem with the pump, which must be fixed
immediately.
Joe
Paul Pinigis wrote:
My point is that there are already so many factors of safety built into
the design of a system that one more is overkill upon overkill. 95% of
fires are controlled with one sprinkler operating, 98% of fires are
controlled with five or less operating, yet we calculate 1,500 square
feet (or 3,000 square feet for military projects), them we overestimate
the friction loss in pipe and fittings, underestimate the water supply,
them worry about adding an additional cushion.
Please, no "what about the other 2%" comments.
Paul J. Pinigis, P.E.
Chief Life Safety Engineer
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of George
Church
Sent: Friday, March 16, 2007 9:56 AM
To: [email protected]
Subject: RE: Minimum Supply Pressure
Well, there ARE a few more considerations.
Was the supply adjusted for lowest tank gradient?
What confidence level do you have in the accuracy of the test data ?
What confidence level do you have that NO additional 90's will be
added?
What is the Owner's tolerance for risk?
NFPA #13 does NOT require a cushion. Good trade practice, flexibility
of
installation changes, common sense, and protection of your boss's
retirement
assets require a cushion of some sort. So may the various AHJs you
face-
water co, fire and code officials, insurance carrier, etc.
So you could be right and fine with .0001 cushion- but in so doing, you
may
find yourself in a box scratching for 2.7 PSi in a .0001 margin when a
duct
doesn't go in as planned, some cable bracing is discovered, ANYTHING.
We deal with a water company that applies a .8 coefficient to all
hydrant
test. If your test was from a .7 hydrant, the supply is overstated and
your
system, upon correction, would be 5 or 6 PSI shy. Or if the tank level
was
3' above lowest tank gradient, your system won't work in August.
Or 4 heads could control the fire and everyone smiles. We just don't
know
EVERYTHING and we can't look into the future. I have trouble sleeping
when
we don't have 10%, and prefer 15 PSI+ on prelims on bid day. We just
analyzed a new site for a customer wanting to use K25s without a pump-
would
you tell him, based on 3.6 PSI cushion and ignorant of bar joist
spacing,
that it would? We're proceeding with a pump, and if things turn out
better
we can omit it, give him a credit for the pump, take some back with the
$^
of k25's, but at least the money's in the job to start with.
When I was assetless and worked for others, I'd consider installing
what
you
have. Now, not without everyone involved knowing it, and not if I was
on
the
hook for the pump or larger piping replacement, or dual feed mains, or
whatever was needed to fix whatever changed and bumped us up. Imagine
going
to an owner with a $50,000 adder and explaining it with "we had to add
a
6"
90 at the top of the riser." Not a situation I'd look forward to !
glc
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Paul
Pinigis
Sent: Friday, March 16, 2007 9:31 AM
To: [email protected]
Subject: RE: Minimum Supply Pressure
If you can achieve 10% without spending your client's money (or your
own) great, but it is not necessary.
Paul J. Pinigis, P.E.
Chief Life Safety Engineer
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Brian
Harris
Sent: Friday, March 16, 2007 9:29 AM
To: [email protected]
Subject: RE: Minimum Supply Pressure
10% is what we go by, based on your numbers your only at around 2% :(
Regards,
Brian Harris
First Defense Fire Protection
Design Engineer
[EMAIL PROTECTED]
704.948.3506 phone
704.948.3507 fax
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Charles
Thurston
Sent: Friday, March 16, 2007 10:19 AM
To: [email protected]
Subject: Mininum Supply Pressure
Hello All,
Let me be the one to start things today.
What is the minimum safety pressure allowed ? I have looked in 13 and
did not find it.... I have a situation where the safety pressure is
0.913 psi.
Basis is:
Hose 250
Static 67.00
Residual 38.00 @ 920.00
Available 40.128 @ demand of 882.87
Requires 39.215 psi
Leaving a safety of 0.913 psi
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